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-rw-r--r--libc/bionic/semaphore.c398
1 files changed, 0 insertions, 398 deletions
diff --git a/libc/bionic/semaphore.c b/libc/bionic/semaphore.c
deleted file mode 100644
index 1fa019e..0000000
--- a/libc/bionic/semaphore.c
+++ /dev/null
@@ -1,398 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-#include <semaphore.h>
-#include <errno.h>
-#include <sys/time.h>
-#include <time.h>
-#include <limits.h>
-
-#include "private/bionic_atomic_inline.h"
-#include "private/bionic_futex.h"
-
-/* In this implementation, a semaphore contains a
- * 31-bit signed value and a 1-bit 'shared' flag
- * (for process-sharing purpose).
- *
- * We use the value -1 to indicate contention on the
- * semaphore, 0 or more to indicate uncontended state,
- * any value lower than -2 is invalid at runtime.
- *
- * State diagram:
- *
- * post(1) ==> 2
- * post(0) ==> 1
- * post(-1) ==> 1, then wake all waiters
- *
- * wait(2) ==> 1
- * wait(1) ==> 0
- * wait(0) ==> -1 then wait for a wake up + loop
- * wait(-1) ==> -1 then wait for a wake up + loop
- *
- */
-
-/* Use the upper 31-bits for the counter, and the lower one
- * for the shared flag.
- */
-#define SEMCOUNT_SHARED_MASK 0x00000001
-#define SEMCOUNT_VALUE_MASK 0xfffffffe
-#define SEMCOUNT_VALUE_SHIFT 1
-
-/* Maximum unsigned value that can be stored in the semaphore.
- * One bit is used for the shared flag, another one for the
- * sign bit, leaving us with only 30 bits.
- */
-#define SEM_MAX_VALUE 0x3fffffff
-
-/* convert a value into the corresponding sem->count bit pattern */
-#define SEMCOUNT_FROM_VALUE(val) (((val) << SEMCOUNT_VALUE_SHIFT) & SEMCOUNT_VALUE_MASK)
-
-/* convert a sem->count bit pattern into the corresponding signed value */
-#define SEMCOUNT_TO_VALUE(sval) ((int)(sval) >> SEMCOUNT_VALUE_SHIFT)
-
-/* the value +1 as a sem->count bit-pattern. */
-#define SEMCOUNT_ONE SEMCOUNT_FROM_VALUE(1)
-
-/* the value -1 as a sem->count bit-pattern. */
-#define SEMCOUNT_MINUS_ONE SEMCOUNT_FROM_VALUE(-1)
-
-#define SEMCOUNT_DECREMENT(sval) (((sval) - (1U << SEMCOUNT_VALUE_SHIFT)) & SEMCOUNT_VALUE_MASK)
-#define SEMCOUNT_INCREMENT(sval) (((sval) + (1U << SEMCOUNT_VALUE_SHIFT)) & SEMCOUNT_VALUE_MASK)
-
-/* return the shared bitflag from a semaphore */
-#define SEM_GET_SHARED(sem) ((sem)->count & SEMCOUNT_SHARED_MASK)
-
-
-int sem_init(sem_t *sem, int pshared, unsigned int value)
-{
- if (sem == NULL) {
- errno = EINVAL;
- return -1;
- }
-
- /* ensure that 'value' can be stored in the semaphore */
- if (value > SEM_MAX_VALUE) {
- errno = EINVAL;
- return -1;
- }
-
- sem->count = SEMCOUNT_FROM_VALUE(value);
- if (pshared != 0)
- sem->count |= SEMCOUNT_SHARED_MASK;
-
- return 0;
-}
-
-
-int sem_destroy(sem_t *sem)
-{
- int count;
-
- if (sem == NULL) {
- errno = EINVAL;
- return -1;
- }
- count = SEMCOUNT_TO_VALUE(sem->count);
- if (count < 0) {
- errno = EBUSY;
- return -1;
- }
- sem->count = 0;
- return 0;
-}
-
-
-sem_t *sem_open(const char *name __unused, int oflag __unused, ...)
-{
- errno = ENOSYS;
- return SEM_FAILED;
-}
-
-
-int sem_close(sem_t *sem)
-{
- if (sem == NULL) {
- errno = EINVAL;
- return -1;
- }
- errno = ENOSYS;
- return -1;
-}
-
-
-int sem_unlink(const char* name __unused)
-{
- errno = ENOSYS;
- return -1;
-}
-
-
-/* Decrement a semaphore's value atomically,
- * and return the old one. As a special case,
- * this returns immediately if the value is
- * negative (i.e. -1)
- */
-static int
-__sem_dec(volatile unsigned int *pvalue)
-{
- unsigned int shared = (*pvalue & SEMCOUNT_SHARED_MASK);
- unsigned int old, new;
- int ret;
-
- do {
- old = (*pvalue & SEMCOUNT_VALUE_MASK);
- ret = SEMCOUNT_TO_VALUE(old);
- if (ret < 0)
- break;
-
- new = SEMCOUNT_DECREMENT(old);
- }
- while (__bionic_cmpxchg((int)(old|shared),
- (int)(new|shared),
- (volatile int *)pvalue) != 0);
- return ret;
-}
-
-/* Same as __sem_dec, but will not touch anything if the
- * value is already negative *or* 0. Returns the old value.
- */
-static int
-__sem_trydec(volatile unsigned int *pvalue)
-{
- unsigned int shared = (*pvalue & SEMCOUNT_SHARED_MASK);
- unsigned int old, new;
- int ret;
-
- do {
- old = (*pvalue & SEMCOUNT_VALUE_MASK);
- ret = SEMCOUNT_TO_VALUE(old);
- if (ret <= 0)
- break;
-
- new = SEMCOUNT_DECREMENT(old);
- }
- while (__bionic_cmpxchg((int)(old|shared),
- (int)(new|shared),
- (volatile int *)pvalue) != 0);
-
- return ret;
-}
-
-
-/* "Increment" the value of a semaphore atomically and
- * return its old value. Note that this implements
- * the special case of "incrementing" any negative
- * value to +1 directly.
- *
- * NOTE: The value will _not_ wrap above SEM_VALUE_MAX
- */
-static int
-__sem_inc(volatile unsigned int *pvalue)
-{
- unsigned int shared = (*pvalue & SEMCOUNT_SHARED_MASK);
- unsigned int old, new;
- int ret;
-
- do {
- old = (*pvalue & SEMCOUNT_VALUE_MASK);
- ret = SEMCOUNT_TO_VALUE(old);
-
- /* Can't go higher than SEM_MAX_VALUE */
- if (ret == SEM_MAX_VALUE)
- break;
-
- /* If the counter is negative, go directly to +1,
- * otherwise just increment */
- if (ret < 0)
- new = SEMCOUNT_ONE;
- else
- new = SEMCOUNT_INCREMENT(old);
- }
- while ( __bionic_cmpxchg((int)(old|shared),
- (int)(new|shared),
- (volatile int*)pvalue) != 0);
-
- return ret;
-}
-
-/* lock a semaphore */
-int sem_wait(sem_t *sem)
-{
- unsigned shared;
-
- if (sem == NULL) {
- errno = EINVAL;
- return -1;
- }
-
- shared = SEM_GET_SHARED(sem);
-
- for (;;) {
- if (__sem_dec(&sem->count) > 0)
- break;
-
- __futex_wait_ex(&sem->count, shared, shared|SEMCOUNT_MINUS_ONE, NULL);
- }
- ANDROID_MEMBAR_FULL();
- return 0;
-}
-
-int sem_timedwait(sem_t *sem, const struct timespec *abs_timeout)
-{
- unsigned int shared;
-
- if (sem == NULL) {
- errno = EINVAL;
- return -1;
- }
-
- /* POSIX says we need to try to decrement the semaphore
- * before checking the timeout value. Note that if the
- * value is currently 0, __sem_trydec() does nothing.
- */
- if (__sem_trydec(&sem->count) > 0) {
- ANDROID_MEMBAR_FULL();
- return 0;
- }
-
- /* Check it as per Posix */
- if (abs_timeout == NULL ||
- abs_timeout->tv_sec < 0 ||
- abs_timeout->tv_nsec < 0 ||
- abs_timeout->tv_nsec >= 1000000000)
- {
- errno = EINVAL;
- return -1;
- }
-
- shared = SEM_GET_SHARED(sem);
-
- for (;;) {
- struct timespec ts;
- int ret;
-
- /* Posix mandates CLOCK_REALTIME here */
- clock_gettime( CLOCK_REALTIME, &ts );
- ts.tv_sec = abs_timeout->tv_sec - ts.tv_sec;
- ts.tv_nsec = abs_timeout->tv_nsec - ts.tv_nsec;
- if (ts.tv_nsec < 0) {
- ts.tv_nsec += 1000000000;
- ts.tv_sec -= 1;
- }
-
- if (ts.tv_sec < 0 || ts.tv_nsec < 0) {
- errno = ETIMEDOUT;
- return -1;
- }
-
- /* Try to grab the semaphore. If the value was 0, this
- * will also change it to -1 */
- if (__sem_dec(&sem->count) > 0) {
- ANDROID_MEMBAR_FULL();
- break;
- }
-
- /* Contention detected. wait for a wakeup event */
- ret = __futex_wait_ex(&sem->count, shared, shared|SEMCOUNT_MINUS_ONE, &ts);
-
- /* return in case of timeout or interrupt */
- if (ret == -ETIMEDOUT || ret == -EINTR) {
- errno = -ret;
- return -1;
- }
- }
- return 0;
-}
-
-/* Unlock a semaphore */
-int sem_post(sem_t *sem)
-{
- unsigned int shared;
- int old;
-
- if (sem == NULL)
- return EINVAL;
-
- shared = SEM_GET_SHARED(sem);
-
- ANDROID_MEMBAR_FULL();
- old = __sem_inc(&sem->count);
- if (old < 0) {
- /* contention on the semaphore, wake up all waiters */
- __futex_wake_ex(&sem->count, shared, INT_MAX);
- }
- else if (old == SEM_MAX_VALUE) {
- /* overflow detected */
- errno = EOVERFLOW;
- return -1;
- }
-
- return 0;
-}
-
-int sem_trywait(sem_t *sem)
-{
- if (sem == NULL) {
- errno = EINVAL;
- return -1;
- }
-
- if (__sem_trydec(&sem->count) > 0) {
- ANDROID_MEMBAR_FULL();
- return 0;
- } else {
- errno = EAGAIN;
- return -1;
- }
-}
-
-/* Note that Posix requires that sem_getvalue() returns, in
- * case of contention, the negative of the number of waiting
- * threads.
- *
- * However, code that depends on this negative value to be
- * meaningful is most probably racy. The GLibc sem_getvalue()
- * only returns the semaphore value, which is 0, in case of
- * contention, so we will mimick this behaviour here instead
- * for better compatibility.
- */
-int sem_getvalue(sem_t *sem, int *sval)
-{
- int val;
-
- if (sem == NULL || sval == NULL) {
- errno = EINVAL;
- return -1;
- }
-
- val = SEMCOUNT_TO_VALUE(sem->count);
- if (val < 0)
- val = 0;
-
- *sval = val;
- return 0;
-}
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